1. Field of the Invention
The invention in general relates to optical systems and, more particularly, to apparatus which allows viewing of a scene simultaneously in a plurality of different wavelengths.
2. Description of Related Art
A variety of optical systems are used, both in the military and commercial fields, for viewing a distant target area so as to detect various targets of interest. Light rays from the target area may include several different wavelengths which must be detected and sensors, responsive to the different wavelengths, are provided for such detection. For this purpose beam splitters are used to direct the light rays to the different sensors.
Beam splitters include those which are spectral filters having certain coatings and substrates which reflect one wavelength band and transmit another band. Such beamsplitters, particularly when refractive optics are used, may be spectrum limited. That is, certain wavelengths may be absorbed by the optics and may not be fully detected by the sensor.
Another method of directing the light rays to the different sensors utilizes a rotating faceted mirror arrangement. Although this arrangement does not use refractive optics, it requires at least a drive motor and associated equipment, and may introduce inertial/slewing delays.
The present invention allows detection of an entire spectrum of interest with minimal optical losses and without the requirement of bulky support equipment.